Questions

Simple CAT5 data run just will not work?

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3 Votes
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Simple CAT5 data run just will not work?

robo_dev
I think I know the answer to this question, I'm just here whining......

I ran a simple 75 foot CAT5 data run, punched it down to a Leviton CAT5 module on each end, using 568A pair sequence, and it just does not work.

Got link light on both ends, but Windows XP status shows packets sent, but no packets received. So DHCP won't work, obviously and neither does PING or anything else.

Open pair, right?

I hooked up my Test-UM LanRover cable tester, it shows PASS and the capacitance measurement is normal. I double checked it with the cable tester, even trying to wiggle the cables in case it is a bad connection. Nope. This cable is perfect.

So my cable tester shows that it's good, from end-to-end, including the patch cables. Tried swapping patch cables, of course.

I get link light at both ends, have tested NIC and swapped ethernet router at other end.

The PC can ping a device on a switch attached directly to the PC, but not the router on the other end, which is pingable. Of course the PC cannot get a DHCP address either.

I plan to just re-terminate the CAT5 jacks....maybe something is not punched down cleanly???

This is a standard 192.168.0.1 network, so I doubt I did anything stupid. Windows firewall is turned off, very plain-jane PC (security DVR).

If all else fails, I pulled a second run of CAT5 cable at the same time, so maybe there is cable damage from installing the cable???

I know, I know, I should have used wireless LAN!
  • +
    2 Votes
    NetMan1958

    Does the patch cable at the other end plug directly into the router or is there a switch first? That is
    PC -> patch cable -> leviton jack -> 75' cable run -> leviton jack -> patch cable -> ? router or switch ?

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    0 Votes
    robo_dev

    Tried it both ways, same result.

    This basic setup is a mini-rack that I setup and tested at my shop, on my network, and it all worked perfectly, with static or DHCP. I bring it to the customer house, run a simple data wire, and it decides to not work.

    Before I get out the diagonal-cutters and put new ends on the cable I intend to try:

    a) plugging a small ethernet switch into the router-end of the connection, just in case somehow the router's ethernet port is just somehow flaky.

    b) plug in a 'pair splitter' Y-cable at each end. This is a device that lets you run two data runs over a single CAT5 run. Basically it will let me try using the other two pairs of the cable, assuming that I simply have a bad connection or a pair of the cable itself is damaged.

    I also ran a second wire to the jack, which is a CAT5E cable. My guess is if I simply give-up and punch down the second wire, it will work like a dream.

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    1 Votes
    philldmc

    If all lights show connection, I'm assuming on both the NIC and router..you might want to double check network settings, for example, did you program a static IP by chance? Is the NIC disabled, etc.

    In addition, I did run into a issue where a client had programmed their router to give only 1 IP address...maybe try resetting the router...

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    0 Votes
    robo_dev

    Good thoughts.

    It works with neither DHCP nor static. I have a device in the rack with the PC (APC power controller), that I can ping or web-connect to, so I am confident that the PC and network settings are valid. I must mention that I've been working with networks for more than 20 years, but I do admit that I can make mistakes.

    The bottom line, I suspect, is that one of the punched-down connections is out of tolerance, and simply cutting off the connection and re-terminating the data run will fix it. Again, the odd thing is that my trusty cable tester says it's a good cable

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    1 Votes
    OH Smeg

    Assuming that the Network is not the issue here have you checked for any possible Interference Sources that could be adversely affecting the Cable?

    I remember one run in a shop that caused an Interment issue, it drove me crazy till I looked next door and found a Dentist with their own X Ray equipment. Apparently whenever they took an X Ray of someones mouth the Network crashed.

    Not likely to be something like that but Power Leads inside walls can cause this to happen as well. Look to see if there is any 3 Phase Equipment on that cable run that is a dead give away for issues with CAT5. I've also seen normal Power Runs too close to network Cables cause this to happen and there have been numerous times where I've had to rerun CAT5 to get around this. Doesn't affect Phone Lines anywhere near as much so if you get a person who pulls Phone Runs they don't be as careful as Network Cable Pullers.

    If you can not run the cable differently you may have to use Shielded Cable. Bit more expensive on the cost of the cable and connectors but it solves a lot of issues.

    Col

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    0 Votes
    rahbm

    An "interment" issue? You are not supposed to BURY the cable , you know!

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    1 Votes
    NetMan1958

    I was thinking that if you were plugging the patch cable directly into the router without a switch in between, you might need a x-over cable but if you have tried it with a switch in between that eliminates that. Let us know what you find out as this is an interesting one.

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    1 Votes
    robo_dev

    This data run is in a house, and I ran it through a crawl space where there are some power lines. I was trying to be careful about avoiding proximity to power cables, but maybe I messed up. I did run a shielded cable that I intend to hookup later for video. I also ran a spare CAT5 cable.

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    1 Votes
    oldbaritone

    Do you have a "real" punch tool, or are you using a plastic freebie included with the connectors? (Or worse, a screwdriver?) You get what you pay for, and freebies usually don't do a very good job. If you're running cable yourself, spend some of your savings to buy decent tools. You don't need the most expensive ones, but get a middle-of-the-line tool at least.

    A simple continuity tester is not enough, and sadly they're the most readily available, inexpensive ones. Does your tester verify correct pairing? Correct Polarity? The moderate-priced testers will test those too. My first guess would be to check the connectors with a magnifying glass, and inspect the connections, cuts, and colors.

    To test the cable completely, you'd need a TDR tester. It would find concealed cable damage as well, but it's more expensive than most DIYers want to spend. It's probably less expensive to pull a new wire.

    When you're pulling cable, if you need to "yank" on it, STOP! You need to go find out why it's jamming, rather than pulling harder. If you don't, cable damage is likely. Kinks and small loops can be a problem in Cat5. And as several folks have mentioned, keep Cat5 away from power cables and high-energy appliances and equipment. Take a different route, and never run a data cable through an existing hole with a power cable.

    Based on your discussion that the computer works properly when plugged directly into the router, it does sound like the problem is in the Cat5 run.

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    0 Votes
    robo_dev

    Excellent ideas. I admit that while I have a 'real' punchdown tool, but I used the little plastic thingie.

    I have a TestUM LanRover tester that seems to work OK...it can measure capacitance and distance, as well well as Pairing. Wish it had a lighted display, but I digress....

    I have miles of extra cable, and I ran a spare CAT5E cable between the two points. I will post the solution when I find it.

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    1 Votes
    CG IT

    while every cable guy will say 568A works, and it does, everything has to be wired 568A. So the biggest problem is all premade patch cords are 568B. so you hook up a 568A to a 568B what do you get? cross over cable. while there's link, maybe, and it will test fine with the lan tester, cross overs don't work on PC to switchports.

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    0 Votes
    DavidMBlackwell

    If both ends of a link are 568A, or both ends are 568B, then you have a straight-through. Doesn't matter if you use two straight through links, one using 568A and the other using 568B. The electrons don't care if the plastic around the wire is orange or green. You only get a crossover if one end of the same link is A and the other is B.

    To address the original problem, EMI, faulty termination on the cable run, wire fault somewhere in the cable maybe it was damaged during installation? Since the equipment (I assume including the patch cables, otherwise add that to the list) all tested out before being connected to the cable run that is where I would be looking for the fault. It could have been damaged during the installation I've seen that happen many times in different ways.

    Is this gigabit ethernet? If so, it uses all four wire pairs rather than just two. I've seen a few problems there that allow the initial negotiation to succeed but cause faults during transmission, or some devices that just won't step down to the slower speeds.

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    0 Votes
    CG IT

    As I said, all premade CAT5e patch cables you buy at a store are 568B. They are not 568A. If you make a home run 568A from a wall jack to the patch panel and use a 568B patch cable [premade bought from a store or dealer] you just created a cross over cable. I've seen it happen where the data cable guys cable the office 568A and the IT guys use premade patch cables and then scratch their heads on why it doesn't work. The contractor says they tested all runs ok, so not their fault, but failed to say they wired the entire office 568A so all those 568B patch cables the IT guys bought won't work.

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    0 Votes
    The DOBC

    Who is the idiot that keeps saying that one run punched 568A and a patch cable wired 568B will make a crossover? I think you need to re-read the books!

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    0 Votes
    CG IT

    I am...

    a cross over is:
    568A hook under/ right to left: brn/brnwht/org/bluwht/blu/orgwht/grn/grnwht on one side.

    568B hook under/ right to left: brn/brnwht/grn/bluwht/blu/grnwht/org/orgwht.

    you wire up the office 568A and buy your standard patch cable from the store and use it which is 568B wiring...what do you get?

    that's a cross over cable:

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    0 Votes
    brucemc123

    You're right... a crossover cable is 568A on one end and 568B on the other end. And a straight-through cable has the same wiring scheme on both ends so that all pin numbers are connected to the same pins on the other side (pin 1 to pin one, pin 2 to pin 2, etc.).

    Computers transmit on the pair connected to pins 1 & 2 and receive on the pair connected to pins 3 & 6. Because of this, hubs and switches need to be wired to receive on the pin 1 & 2 pair and transmit on the 3 & 6 pair. But if you want to connect 2 computers directly to each other with one cable you need a crossover cable (568A on one end and 568B on the other) so both computers won't be trying to transmit on Pins 1 & 2 and receive on pins 3 & 6. The crossover cable connects the transmitting pair on one end to the receiving pair on the other end.

    Most patch cables are 568B but I've seen 568A used (on both ends) and it works the same because as long as both ends are the same it's wired straight-through. And if you connect 2 straight-through cables (even if one is 568A straight-through and the other is 568B straight-through) you still send the signals straight through because what goes in on a particular pin number still comes out on the same pin number at the other end.

    When in doubt... check Wikipedia. :)

    http://en.wikipedia.org/wiki/Ethernet_crossover_cable

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    2 Votes
    CG IT

    .

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    1 Votes
    greg.goss

    Does another computer work on the cable?
    If not, verify a computer works plugged in at the very beginning of the run.
    Keep moving back down the cable run (plugging in at each connection/junction point) until it no longer connects.

    Are there florescent lights along the run? Motors? fans?

    +
    1 Votes
    brucemc123

    Are you connecting two devices that need a crossover connection? Most modern hubs and switches are auto-sensing (automatic MDI/MDI-X configuration) but some have a special "uplink" port or even a manual switch when crossover is necessary and some have no crossover capability at all so a crossover cable is required. It's an easy thing to try just in case. A good explanation can be found on Wikipedia at:
    http://en.wikipedia.org/wiki/Ethernet_crossover_cable

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    0 Votes
    robo_dev

    Thanks, At the far-end I've tried it with both the NIC itself and a switch that does auto-crossover. Since I get link on both ends and my cable tester says my pairing is correct, I think it's just a bad punchdown, damaged cable, or interference.

  • +
    2 Votes
    NetMan1958

    Does the patch cable at the other end plug directly into the router or is there a switch first? That is
    PC -> patch cable -> leviton jack -> 75' cable run -> leviton jack -> patch cable -> ? router or switch ?

    +
    0 Votes
    robo_dev

    Tried it both ways, same result.

    This basic setup is a mini-rack that I setup and tested at my shop, on my network, and it all worked perfectly, with static or DHCP. I bring it to the customer house, run a simple data wire, and it decides to not work.

    Before I get out the diagonal-cutters and put new ends on the cable I intend to try:

    a) plugging a small ethernet switch into the router-end of the connection, just in case somehow the router's ethernet port is just somehow flaky.

    b) plug in a 'pair splitter' Y-cable at each end. This is a device that lets you run two data runs over a single CAT5 run. Basically it will let me try using the other two pairs of the cable, assuming that I simply have a bad connection or a pair of the cable itself is damaged.

    I also ran a second wire to the jack, which is a CAT5E cable. My guess is if I simply give-up and punch down the second wire, it will work like a dream.

    +
    1 Votes
    philldmc

    If all lights show connection, I'm assuming on both the NIC and router..you might want to double check network settings, for example, did you program a static IP by chance? Is the NIC disabled, etc.

    In addition, I did run into a issue where a client had programmed their router to give only 1 IP address...maybe try resetting the router...

    +
    0 Votes
    robo_dev

    Good thoughts.

    It works with neither DHCP nor static. I have a device in the rack with the PC (APC power controller), that I can ping or web-connect to, so I am confident that the PC and network settings are valid. I must mention that I've been working with networks for more than 20 years, but I do admit that I can make mistakes.

    The bottom line, I suspect, is that one of the punched-down connections is out of tolerance, and simply cutting off the connection and re-terminating the data run will fix it. Again, the odd thing is that my trusty cable tester says it's a good cable

    +
    1 Votes
    OH Smeg

    Assuming that the Network is not the issue here have you checked for any possible Interference Sources that could be adversely affecting the Cable?

    I remember one run in a shop that caused an Interment issue, it drove me crazy till I looked next door and found a Dentist with their own X Ray equipment. Apparently whenever they took an X Ray of someones mouth the Network crashed.

    Not likely to be something like that but Power Leads inside walls can cause this to happen as well. Look to see if there is any 3 Phase Equipment on that cable run that is a dead give away for issues with CAT5. I've also seen normal Power Runs too close to network Cables cause this to happen and there have been numerous times where I've had to rerun CAT5 to get around this. Doesn't affect Phone Lines anywhere near as much so if you get a person who pulls Phone Runs they don't be as careful as Network Cable Pullers.

    If you can not run the cable differently you may have to use Shielded Cable. Bit more expensive on the cost of the cable and connectors but it solves a lot of issues.

    Col

    +
    0 Votes
    rahbm

    An "interment" issue? You are not supposed to BURY the cable , you know!

    +
    1 Votes
    NetMan1958

    I was thinking that if you were plugging the patch cable directly into the router without a switch in between, you might need a x-over cable but if you have tried it with a switch in between that eliminates that. Let us know what you find out as this is an interesting one.

    +
    1 Votes
    robo_dev

    This data run is in a house, and I ran it through a crawl space where there are some power lines. I was trying to be careful about avoiding proximity to power cables, but maybe I messed up. I did run a shielded cable that I intend to hookup later for video. I also ran a spare CAT5 cable.

    +
    1 Votes
    oldbaritone

    Do you have a "real" punch tool, or are you using a plastic freebie included with the connectors? (Or worse, a screwdriver?) You get what you pay for, and freebies usually don't do a very good job. If you're running cable yourself, spend some of your savings to buy decent tools. You don't need the most expensive ones, but get a middle-of-the-line tool at least.

    A simple continuity tester is not enough, and sadly they're the most readily available, inexpensive ones. Does your tester verify correct pairing? Correct Polarity? The moderate-priced testers will test those too. My first guess would be to check the connectors with a magnifying glass, and inspect the connections, cuts, and colors.

    To test the cable completely, you'd need a TDR tester. It would find concealed cable damage as well, but it's more expensive than most DIYers want to spend. It's probably less expensive to pull a new wire.

    When you're pulling cable, if you need to "yank" on it, STOP! You need to go find out why it's jamming, rather than pulling harder. If you don't, cable damage is likely. Kinks and small loops can be a problem in Cat5. And as several folks have mentioned, keep Cat5 away from power cables and high-energy appliances and equipment. Take a different route, and never run a data cable through an existing hole with a power cable.

    Based on your discussion that the computer works properly when plugged directly into the router, it does sound like the problem is in the Cat5 run.

    +
    0 Votes
    robo_dev

    Excellent ideas. I admit that while I have a 'real' punchdown tool, but I used the little plastic thingie.

    I have a TestUM LanRover tester that seems to work OK...it can measure capacitance and distance, as well well as Pairing. Wish it had a lighted display, but I digress....

    I have miles of extra cable, and I ran a spare CAT5E cable between the two points. I will post the solution when I find it.

    +
    1 Votes
    CG IT

    while every cable guy will say 568A works, and it does, everything has to be wired 568A. So the biggest problem is all premade patch cords are 568B. so you hook up a 568A to a 568B what do you get? cross over cable. while there's link, maybe, and it will test fine with the lan tester, cross overs don't work on PC to switchports.

    +
    0 Votes
    DavidMBlackwell

    If both ends of a link are 568A, or both ends are 568B, then you have a straight-through. Doesn't matter if you use two straight through links, one using 568A and the other using 568B. The electrons don't care if the plastic around the wire is orange or green. You only get a crossover if one end of the same link is A and the other is B.

    To address the original problem, EMI, faulty termination on the cable run, wire fault somewhere in the cable maybe it was damaged during installation? Since the equipment (I assume including the patch cables, otherwise add that to the list) all tested out before being connected to the cable run that is where I would be looking for the fault. It could have been damaged during the installation I've seen that happen many times in different ways.

    Is this gigabit ethernet? If so, it uses all four wire pairs rather than just two. I've seen a few problems there that allow the initial negotiation to succeed but cause faults during transmission, or some devices that just won't step down to the slower speeds.

    +
    0 Votes
    CG IT

    As I said, all premade CAT5e patch cables you buy at a store are 568B. They are not 568A. If you make a home run 568A from a wall jack to the patch panel and use a 568B patch cable [premade bought from a store or dealer] you just created a cross over cable. I've seen it happen where the data cable guys cable the office 568A and the IT guys use premade patch cables and then scratch their heads on why it doesn't work. The contractor says they tested all runs ok, so not their fault, but failed to say they wired the entire office 568A so all those 568B patch cables the IT guys bought won't work.

    +
    0 Votes
    The DOBC

    Who is the idiot that keeps saying that one run punched 568A and a patch cable wired 568B will make a crossover? I think you need to re-read the books!

    +
    0 Votes
    CG IT

    I am...

    a cross over is:
    568A hook under/ right to left: brn/brnwht/org/bluwht/blu/orgwht/grn/grnwht on one side.

    568B hook under/ right to left: brn/brnwht/grn/bluwht/blu/grnwht/org/orgwht.

    you wire up the office 568A and buy your standard patch cable from the store and use it which is 568B wiring...what do you get?

    that's a cross over cable:

    +
    0 Votes
    brucemc123

    You're right... a crossover cable is 568A on one end and 568B on the other end. And a straight-through cable has the same wiring scheme on both ends so that all pin numbers are connected to the same pins on the other side (pin 1 to pin one, pin 2 to pin 2, etc.).

    Computers transmit on the pair connected to pins 1 & 2 and receive on the pair connected to pins 3 & 6. Because of this, hubs and switches need to be wired to receive on the pin 1 & 2 pair and transmit on the 3 & 6 pair. But if you want to connect 2 computers directly to each other with one cable you need a crossover cable (568A on one end and 568B on the other) so both computers won't be trying to transmit on Pins 1 & 2 and receive on pins 3 & 6. The crossover cable connects the transmitting pair on one end to the receiving pair on the other end.

    Most patch cables are 568B but I've seen 568A used (on both ends) and it works the same because as long as both ends are the same it's wired straight-through. And if you connect 2 straight-through cables (even if one is 568A straight-through and the other is 568B straight-through) you still send the signals straight through because what goes in on a particular pin number still comes out on the same pin number at the other end.

    When in doubt... check Wikipedia. :)

    http://en.wikipedia.org/wiki/Ethernet_crossover_cable

    +
    2 Votes
    CG IT

    .

    +
    1 Votes
    greg.goss

    Does another computer work on the cable?
    If not, verify a computer works plugged in at the very beginning of the run.
    Keep moving back down the cable run (plugging in at each connection/junction point) until it no longer connects.

    Are there florescent lights along the run? Motors? fans?

    +
    1 Votes
    brucemc123

    Are you connecting two devices that need a crossover connection? Most modern hubs and switches are auto-sensing (automatic MDI/MDI-X configuration) but some have a special "uplink" port or even a manual switch when crossover is necessary and some have no crossover capability at all so a crossover cable is required. It's an easy thing to try just in case. A good explanation can be found on Wikipedia at:
    http://en.wikipedia.org/wiki/Ethernet_crossover_cable

    +
    0 Votes
    robo_dev

    Thanks, At the far-end I've tried it with both the NIC itself and a switch that does auto-crossover. Since I get link on both ends and my cable tester says my pairing is correct, I think it's just a bad punchdown, damaged cable, or interference.